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My dog who takes heart medication ate one foxglove leaf — does his condition make it more dangerous?

Dogs · Emergency guide

Last reviewed: 2026-09-05 · Reference ranges: ASPCA, Pet Poison Helpline & Merck Veterinary Manual

Short answer

Yes, it is far more dangerous because foxglove contains cardiac glycosides similar to some heart medicines. In a dog already on medication, the combined effect can dangerously disrupt heart rhythm and lead to collapse or cardiac arrest. Even a single leaf is highly toxic, and symptoms like vomiting, weakness, or an irregular heartbeat can appear quickly. This is an absolute emergency — go to the vet immediately and bring the plant sample with you, and be sure to tell them about your dog's current heart medication.

Why is this dangerous?

Foxglove (Digitalis purpurea) contains digitoxin and digoxin, the same drugs used in human heart medicine — but in uncontrolled amounts. They slow conduction through the heart and can cause heart block, arrhythmias and cardiac arrest.

Leaves are most toxic and remain dangerous when dried or wilted, including in floral arrangements and compost.

Why speed matters

Delaying care significantly worsens outcomes. Some signs appear hours or days later, so "looks fine right now" is not a reason to wait.

Signs to watch for

  • Vomiting, drooling, loss of appetite
  • Slow, weak or irregular heartbeat
  • Wobbliness, collapse, fainting
  • Dilated pupils, blurred vision behaviour (bumping into things)
  • Seizures and sudden death in severe cases

What to do right now

  1. This is an emergency even if the pet looks normal — call and go now.
  2. Bring plant material so the vet can confirm it is foxglove and not a look-alike.
  3. Never induce vomiting at home for a suspected cardiac toxin.
  4. Tell the vet about any heart medication the pet already takes.
If your pet shows any of the signs above, go to the nearest emergency vet now and call ahead.

The step-by-step response, from the first minute to the vet visit, is in our Foxglove (Digitalis) emergency guide.

Open the full emergency guide: Foxglove (Digitalis) →